1. Field of the Invention
This disclosure relates generally to systems, apparatus and methods for geofences, and more particularly to creating and applying a geofence based on WLAN signals.
2. Background
Today's geofence is defined by a circle with a center determined by a GNSS or GPS coordinate (latitude and longitude) and having a radius (R). A mobile device includes a low power consuming modem and a high power consuming application processor. The low power consuming modem contains a global navigation satellite system (GNSS) or global positioning system (GPS) receiver. The high power consuming application processor contains a specific application. The mobile device uses the GNSS receiver to determine when a current location of the mobile device has crossed between inside and outside a geofence. When the mobile device determines it is leaving or entering a geofenced area, the mobile device wakes the high power consuming application processor to execute the specific application.
The above technique will allow high power processor to sleep for most of time, thus saving power. However, there are a few key problems that cannot be solved by this approach. First of all, a GNSS fix may be difficult or impossible (e.g., from deep within a building. Second, a position of a WiFi access point may be unknown. Third, a user does not know GPS coordinate (latitude and longitude) needed to define a geofence. Instead, the user only knows a relative location or physical address (e.g., my living room or a particular set of conference rooms). Fourth, a geofence may not have a fixed location (e.g., on a truck, train or ship). Fifth, a geofence may not be circular such as free formed or other irregular shape. Sixth, transmitting an entire geofence requires excessive power and/or band width usage.
What is needed is a means to create and use a geofence when: (1) GNSS signals are unavailable; (2) an absolute location of a WiFi access point is unknown; (3) GNSS coordinates of a geofence are unknown; (4) a geofence has a non-fixed location; (5) a geofence is of an irregular shape; or (6) power and/or transmission costs need to be wherein the absolute information comprises location information of a plurality of transmitters.